Climate Change Adaptation of Urban Stormwater Infrastructure

Status:  Complete
Report Date:  08/16/2023


Stormwater runoff from intense rainstorms is controlled by MnDOT’s network of pipes, retention ponds and swales to protect communities, roads, bridges and natural resources from flooding. Severe storms are projected to increase, however, and predicted development will increase impervious land area and potentially runoff. MnDOT wanted to ensure runoff is adequately managed. New research updates rainfall projections and analyzes cost-effective stormwater management strategies for the future. Investigators modeled how effectively a variety of methods to control runoff would prevent flooding in three watersheds during severe storms. The modeled storms involved intense rainfall over a few hours and are not expected to happen very often (once every 10 or more years). Stormwater control strategies examined included infiltration basins, retention ponds and stormwater pipes. Calculated costs of constructing and maintaining the strategies over a 20-year life cycle identified new stormwater ponds as generally the most cost-effective strategy. However, infiltration basins with deep-rooted vegetation would work well to control stormwater from more common storms with rainfall occurring more uniformly over a day’s time. MnDOT will continue to assess the adequacy of its stormwater infrastructure as storm patterns change and development occurs around the state.

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